Light emitting device and method for producing the same

ABSTRACT

A light emitting device includes a semiconductor light emitting element; and a light reflective member having a multilayer structure and covering the side faces of the semiconductor light emitting element. The light reflective member includes: a first layer disposed on an inner, semiconductor light emitting element side, the first layer comprising a light-transmissive resin containing a light reflective substance, and a second layer disposed in contact with an outer side of the first layer, the second layer comprising a light-transmissive resin containing the light reflective substance at a lower content than that of the first layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.14/866,317, filed on Sep. 25, 2015, which claims priority to JapanesePatent Application No. 2014-197340, filed on Sep. 26, 2014, thedisclosures of which are hereby incorporated by reference in theirentireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a light emitting device having asemiconductor light emitting element and a light reflective member, anda method of producing the same.

2. Description of Related Art

Light emitting devices provided with a reflective layer on the sidefaces of an LED (light emitting diode), which is a semiconductor lightemitting element, for efficient upward emission have been proposed. Forexample, Japanese Unexamined Patent Application Publication No.2012-243822 (“JP '822”) discloses a light emitting device in which theside faces of the LED chip are covered with a resin member to whichreflectance is imparted by including a light reflective filler in alight-transmissive resin.

Japanese Patent Publication No. 4778085 (“JP '085”) discloses a lightemitting device in which a package is formed with a resin material thatcontains at least 46 wt % of a light reflective filler, and an LED ismounted in the recess of the package.

In cases where a reflective layer is formed with a white resin to whichreflectance is imparted by having the light-transmissive resin contain alight reflective filler, as in the light emitting device disclosed in JP'822, a portion of the light incident on the reflective layeroccasionally passes through and leaks out.

In order to achieve an adequate reflectance using a white resin,moreover, a light reflective filler must be added at a high content, asin the case, for example, of the resin material disclosed in JP '085.Adding a light reflective filler at a high content, however, reduces thefluidity of the resin material, making it hard, and results in reducedformability. This also makes the molding brittle, thereby reducing itsreliability.

For these reasons, it was difficult to form a reflective layer (i.e.light reflective member) that had both good reflectance and highreliability on the side faces of a semiconductor light emitting elementusing a resin material.

SUMMARY OF THE INVENTION

Embodiments of the present invention have been developed in view of theabove-mentioned problems, and it is an object of certain embodiments ofthe invention to provide a light emitting device having a lightreflective member that has both good reflectance and high reliabilityusing a material made of a resin and a light reflective substance, andto provide a method of producing the same.

A light emitting device according to one embodiment of the presentinvention includes a semiconductor light emitting element and amulti-layered light reflective member that covers side faces of thesemiconductor light emitting element. The light reflective memberincludes a first layer, which is disposed on the inner side, thesemiconductor light emitting element side, and made of alight-transmissive resin containing a light reflective substance, and asecond layer, which is disposed in contact with the outer side of thefirst layer, and made of a light-transmissive resin having a lowercontent of the light reflective substance than that of the first layer.

A light emitting device production method according to one embodiment ofthe invention is a production method for a light emitting device inwhich the side faces of the semiconductor light emitting element arecovered by a multilayer-structured light reflective member, and has asemiconductor light emitting element mounting step to mount thesemiconductor light emitting element on a substrate; a first layerforming step to form a first layer of the light reflective member madeof a light-transmissive resin containing a light reflective substance soas to cover the upper and side faces of the semiconductor light emittingelement; a second layer forming step to form a second layer of the lightreflective member made of a light-transmissive resin containing thelight reflective substance at a lower content than the first layer onthe first layer; and a light reflective member removing step to removethe first layer and the second layer formed on the upper face of thesemiconductor light emitting element.

A light emitting device production method according to anotherembodiment of the invention is a production method for a light emittingdevice in which the side faces of the semiconductor light emittingelement are covered by a light reflective member having a multilayerstructure, and has a semiconductor light emitting element mounting stepto mount the semiconductor light emitting element on a sheet having anadhesive surface so that the sheet and the light extraction face of thesemiconductor light emitting element oppose one another; alight-transmissive member forming step to form a light-transmissivemember disposed in contact with the side faces of the semiconductorlight emitting element and having an outer face sloping outwardly in thelight extracting direction with respect to the thickness of thesemiconductor light emitting element; a first layer forming step to forma first layer of the light reflective member made of alight-transmissive resin containing a light reflective substance so asto cover the upper face of the semiconductor light emitting element andthe outer face of the light-transmissive member; a second layer formingstep to form a second layer of the light reflective member made of alight-transmissive resin having a lower content of the light reflectivesubstance than the first layer on said first layer; a light reflectivemember removing step to expose the electrodes of the semiconductor lightemitting element by removing the first and second layers formed on theupper face of the semiconductor light emitting element; and a sheetremoving step to remove the sheet by detaching from the semiconductorlight emitting element and the light-transmissive member.

The light emitting devices according to certain embodiments of theinvention can increase not only frontal luminance, but also thereliability of the light emitting device.

The light emitting device production method according to certainembodiments of the invention can produce a light emitting device havingboth high frontal luminance and high reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a) and (b) are schematic views showing a light emitting deviceaccording to a first embodiment of the invention where (a) is a planview, and (b) is a sectional view at line I-I in (a).

FIG. 2 is a schematic sectional view showing an example of asemiconductor light emitting element configuration employed in the lightemitting device according to the first embodiment of the invention.

FIG. 3 is a graph showing the relationship between the thickness of alight reflective member and the reflectance for various contents of alight reflective substance.

FIG. 4 is a flowchart showing the production method for the lightemitting device according to the first embodiment of the invention.

FIGS. 5(a) and (b) are schematic views showing the configuration of amounting substrate prepared in a mounting substrate preparation step ofthe production method for the light emitting device according to thefirst embodiment of the invention where (a) is a plan view, and (b) is asectional view at line II-II in (a).

FIGS. 6(a) and (b) are schematic views showing the semiconductor lightemitting element mounting step of the production method for the lightemitting device according to the first embodiment of the invention where(a) is a plan view, and (b) is a sectional view at line in (a).

FIGS. 7 (a)-(d) are schematic sectional views showing the followingsteps of the production method for the light emitting devices accordingto the first embodiment: (a) first layer forming step, (b) second layerforming step, (c) light reflective member removing step, and (d)wavelength conversion member forming step.

FIGS. 8(a) and (b) are schematic views showing the singulation step forthe light emitting device according to the first embodiment of theinvention where (a) is a plan view, and (b) is a sectional view at linein (a).

FIG. 9 is a schematic sectional view showing the configuration of thelight emitting device according to a second embodiment.

FIG. 10 is a flowchart showing the production method for the lightemitting device according to the second embodiment of the invention.

FIGS. 11 (a)-(c) are schematic sectional views showing the followingsteps of the production method for the light emitting device accordingto the second embodiment of the invention: (a) semiconductor lightemitting element mounting step, (b) second layer forming step, and (c)light reflective member removing step.

FIG. 12 is a schematic sectional view enlarging a section of the lightemitting device according to a third embodiment of the invention.

FIGS. 13(a) and (b) are schematic views showing the configuration of thelight emitting device according to a fourth embodiment of the inventionwhere (a) is a plan view, and (b) is a sectional view at line IV-IV in(a).

FIG. 14 is a flowchart showing the production method for the lightemitting device according to the fourth embodiment of the invention.

FIGS. 15 (a) and (b) are schematic views showing the semiconductor lightemitting element mounting step of the production method for the lightemitting device according to the fourth embodiment of the inventionwhere (a) is a plan view, and (b) is a sectional view at line V-V in(a).

FIGS. 16 (a) and (b) are schematic drawings showing a light-transmissivemember forming step for the light emitting device according to thefourth embodiment of the invention where (a) is a plan view, and (b) isa sectional view at line V-V in (a).

FIGS. 17 (a)-(d) are schematic sectional views showing the followingsteps of the production method for the light emitting device accordingto the fourth embodiment of the invention: (a) first layer forming step,(b) second layer forming step, (c) light reflective member removingstep, and (d) sheet removing step.

FIGS. 18 (a) and (b) are schematic sectional views showing the followingsteps of the production method for the light emitting device accordingto the fourth embodiment of the invention: (a) wavelength conversionmember forming step, and (b) singulation step.

FIG. 19 is a schematic sectional view showing the configuration of thelight emitting device according to a fifth embodiment of the invention.

FIG. 20 is a flowchart showing the production method for the lightemitting device according to the fifth embodiment of the invention.

FIG. 21 (a)-(c) are schematic sectional views showing the followingsteps of the production method for the light emitting device accordingto the fifth embodiment of the invention: (a) light-transmissive membercoating step, (b) semiconductor light emitting element mounting step,and (c) wavelength conversion member forming step.

DETAILED DESCRIPTION

The light emitting devices and the production method according toembodiments of the invention, will be explained below.

The drawings referenced in the explanation below are schematicrepresentations of the embodiments of the invention. As such, themembers might not be drawn to scale, the spacing and their relativepositions may be exaggerated, or a part of a member might be omitted.

Moreover, the scale or spacing of the members might not match betweenthe plan and sectional views. Also, in the explanation below, elementshaving the same designations and reference numerals are basically of thesame material, for which detailed explanations are omitted wheneverappropriate.

First Embodiment

[Light Emitting Device Configuration]

First, the configuration of the light emitting device according to afirst embodiment of the present invention will be explained withreference to FIGS. 1 and 2.

As shown in FIG. 1, the light emitting device 100 of this embodiment hasa semiconductor light emitting element 1 (hereinafter referred to as“light emitting element” when appropriate), a light reflective member 2,a wavelength conversion member 3, and a mounting substrate (submount) 9.

The light emitting element 1 is flip-chip mounted on a mountingsubstrate 9 via a conductive adhesive material 93, such as solder.

On the side faces of the light emitting element 1, a light reflectivemember 2 having a first layer 21 and second layer 22 is provided toincrease the light extraction efficiency from the upper face of thelight emitting element 1.

On the upper face of the light emitting element 1, moreover, awavelength conversion member 3 is provided to allow at least a portionof the light emitted from the light emitting element 1 to exit afterbeing converted into light of a different wavelength.

Each element of the light emitting device 100 will be sequentiallyexplained in detail subsequently.

The light emitting element 1 is an LED chip suitably configured for flipchip mounting, which has roughly a rectangular parallelepiped shape (anoblong rectangle in a plan view), and is provided with an n-sideelectrode 13 and p-side electrode 15 on one face to be connected to thewiring electrodes 92 n and 92 p of the mounting substrate (submount) 9via a conductive adhesive material 93.

Now, an example of the configuration of the light emitting element 1will be explained with reference to FIG. 2. In FIG. 2, the chip isoriented to have the face having the n-side electrode 13 and p-sideelectrode 15 on the upper side, what is shown in FIG. 1(b) is turnedupside down. In FIG. 1, the later discussed FIG. 6, or the like,moreover, the illustration of the configuration of the light emittingelement 1 is simplified.

As shown in FIG. 2, the light emitting element 1 has a growth substrate11, semiconductor stack 12, n-side electrode 13, full surface electrode14, p-side electrode 15, and insulator 16.

The light emitting element 1 has a semiconductor stack 12 in which ann-type semiconductor layer 12 n and p-type semiconductor layer 12 p arestacked on one face of the growth substrate 11. The semiconductor stack12 is adapted to emit light when current flows between the n-sideelectrode 13 and p-side electrode 15 by connecting to an external powersupply, and is preferably provided with an active layer 12 a between then-type semiconductor layer 12 n and p-type semiconductor layer 12 p.

The growth substrate 11 is provided to allow the semiconductor stack 12to be epitaxially grown. The growth substrate 11 can be formed with anysubstrate material capable of allowing for the epitaxial growth of thesemiconductor stack 12, and its size or thickness is not particularlylimited. In cases where the semiconductor stack 12 is formed using anitride semiconductor such as GaN (gallium nitride), for example, thesesubstrate materials include an insulating substrate, such as c-plane,r-plane, or a-plane sapphire, and spinel (MgAl₂O₄), as well as siliconcarbide (SiC), ZnS, ZnO, Si, GaAs, diamond, and an oxide substrate, suchas lithium niobate, neodymium gallate, and the like, that form a latticejunction with a nitride semiconductor. It is preferable to use amaterial having good light transmissive property for the growthsubstrate 11 to configure the light emitting element 1 suitable for flipchip mounting.

In the semiconductor stack 12, an n-type semiconductor layer 12 n whichincludes an active layer 12 a, and p-type semiconductor layer 12 p arestacked. The semiconductor stack 12 is provided with a region where boththe p-type semiconductor layer 12 p and the active layer 12 a arepartially absent, that is, a region recessed from the surface of thep-type semiconductor layer 12 p (this region is referred to as the“stepped section 12 b”). At the bottom face of the stepped section 12 b,an n-side electrode 13 which is electrically connected to the n-typesemiconductor layer 12 n is provided. A full surface electrode 14 havinggood electrical conductivity and light reflectance is providedsubstantially across the entire upper surface of the p-typesemiconductor layer 12 p. The surface of the semiconductor stack 12 iscovered with an insulator 16 directly or via the full surface electrode14, except for a portion of the bottom of the stepped section 12 b and aportion of the upper face of the full surface electrode 14.

For the semiconductor stack 12 (n-type semiconductor layer 12 n, activelayer 12 a, and p-type semiconductor layer 12 p),In_(X)Al_(Y)Ga_(1-X-Y)N (0≦X, 0≦Y, X+Y<1), or the like, is suitablyused. These semiconductor layers, moreover, may individually have asingle layer structure, a multilayer structure having layers ofdifferent compositions and film thicknesses, or a superlatticestructure. The active layer 12 a, in particular, preferably has a singlequantum well or multi-quantum well structure where thin films arestacked that generates quantum effects.

The full surface electrode 14 is provided to substantially cover theentire upper face of the p-type semiconductor layer 12 p. The fullsurface electrode 14 is a conductive layer for diffusing the currentsupplied via the p-side electrode 15, which is disposed in one portionof the upper face, across the entire surface of the p-type semiconductorlayer 12 p. The full surface electrode 14, moreover, has goodreflectance to also function as a reflective film to reflect the lightemitted by the light emitting element 1 downwardly (in FIG. 1(b),upwardly) towards the light extraction face.

For the full surface electrode 14, a metal material having goodconductivity and reflectivity can be used. As a metal material havinggood reflectivity particularly in the visible light range, Ag, Al, or analloy having these metals as main components can be suitably used. Forthe full surface electrode 14, moreover, these metal materials in asingle layer, or multiple layers, can be used. When Ag which is prone tomigration is used as the lower layer of the full surface electrode 14(on the p-type semiconductor layer 12 p side), it is preferable to coverthe lower layer with an upper layer made of a metal material having goodconductivity and barrier properties, such as Al, Ti, W, Au, or the like.

The n-side electrode 13 is provided to be electrically connected to then-type semiconductor layer 12 n within the opening 16 n of the insulator16 at the bottom face of the stepped section 12 b of the semiconductorstack 12. The p-side electrode 15 is provided to be electricallyconnected to the full surface electrode 14 within the opening 16 p ofthe insulator 16 on the upper face of the full surface electrode 14. Then-side electrode 13 and p-side electrode 15 are pad electrodes to supplythe current from the outside to the n-type semiconductor layer 12 n andp-type semiconductor layer 12 p via the full surface electrode 14,respectively.

The n-side electrode 13 and p-side electrode 15 are provided in theextended areas of the full surface electrode 14 via the insulator 16.

For the n-side electrode 13 and p-side electrode 15, a metal materialcan be used, and for example, a single metal, such as Ag, Al, Ni, Rh,Au, Cu, Ti, Pt, Pd, Mo, Cr, W, or the like, and their alloys can besuitably used. For the n-side electrode 13 and p-side electrode 15,moreover, a single layer or multiple layers of these metal materials canbe used.

The insulator 16 covers the upper and side faces of the semiconductorstack 12 and full surface electrode 14, and functions as a protectiveand antistatic film of the light emitting element 1. The insulator 16has an opening 16 n in one portion of the bottom face of the steppedsection 12 b, and an opening 16 p in one portion of the upper face ofthe full surface electrode 14. In the large area of the upper face ofthe insulator 16, n-side electrode 13 and p-side electrode 15 areprovided so as to extend complementarily to one another.

For the insulator 16, a metal oxide or metal nitride can be used.

For example, at least one metal oxide or metal nitride selected from thegroup consisting of Si, Ti, Zr, Nb, Ta, and Al can be suitably used.

The light emitting element 1 shown in FIG. 2 is one example; the outershape, and the regions where the stepped section 12 b, n-side electrode13, p-side electrode 15, and the like are provided can be suitablymodified.

Referring back to FIG. 1, the explanation of the configuration of thelight emitting device 100 will be continued.

The light reflective member 2 is provided to cover the side faces of thelight emitting element 1, and to reflect the light exiting from the sidefaces of the light emitting element 1 into the light emitting element 1.Here, the light reflective member 2 is provided on the side faces of thesemiconductor stack 12 and growth substrate 11, which are the members inwhich the light propagates. This can increase the emission luminance atthe upper face of the light emitting element 1, which is the lightextraction face.

The light reflective member 2 shown in FIG. 1 have a first layer 21provided on the inner side, that is, the light emitting element 1 side,and a second layer 22 provided on the outer side of the first layer 21.

The first layer 21 and second layer 22 are formed by having alight-transmissive resin contain particles of a light reflectivesubstance.

As previously discussed, as the light reflective substance contentincreases, the reflectance increases, but the resin becomes hard due tothe decrease of the fluidity of the resin material, resulting in reducedformability. This also makes the molding brittle, thereby reducing itsreliability. In this embodiment, therefore, the first layer 21 is formedwith a high light reflective substance content to achieve higherreflectance than the second layer 22, and in a smaller thickness thanthe second layer 22 so that the light reflective member 2 does notbecome brittle as a whole. At the same time, the second layer 22 isprovided with a light reflective substance content in the range capableof achieving adequate formability, and is formed as a thick film tosecure the mechanical strength of the light reflective member 2 as awhole. Both reflectance and formability can be successfully achieved byconfiguring the light reflective member 2 in this manner. By having sucha light reflective member 2, the light emitting device 100 can increaseboth its frontal (extracting direction) emission luminance andreliability.

The light reflective substance content of the first layer 21 can bedetermined in accordance with its thickness. The first layer 21 isreinforced by the second layer 22 from the outer side so as to maintainits shape. Thus, the first layer 21 can have the light reflectivesubstance at a higher content than the second layer 22 to achieve higherreflectance than the second layer 22.

For good reflectance, the light reflective substance content of thefirst layer 21 is preferably set to at least 60 mass %, more preferablyat least 90 mass %. Moreover, the light reflective substance content ofthe first layer 21 is preferably set to 99 mass % at most to allow thelight reflective substance particles to be adequately bound together.

However, the light reflective substance content of the first layer 21may exceed 99 mass %, as long as adequate adhesion is achieved betweenthe first layer 21 and the side surfaces of the light emitting element1.

In order to form the first layer 21 into a stable shape and at a stablethickness accuracy, it is preferable to set the thickness to at least 2μm, more preferably at least 10 μm.

Moreover, it is preferable to form the first layer 21 as a thick film tothe extent that the shape can be maintained with the reinforcementprovided by the second layer 22. For this purpose, the thickness of thefirst layer 21 is preferably 30 μm at most.

It is preferable for the second layer 22 to have a high content of thelight reflective substance to the extent that it achieves adequateformability using a forming method involving a mold, frame, or the like.

The light reflective substance content of the second layer 22 ispreferably set to at least 10 mass %, but 60 mass % at most, morepreferably at least 20 mass %, but 50 mass % at most.

However, in cases where the first layer 21 can be formed with adequatelyhigh reflectance (for example, 90% or more), the light reflectivesubstance content of the second layer 22 may be set to about 1 mass %,or none.

The second layer 22, moreover, is preferably formed in the thicknesscapable of adequately reinforcing the first layer 21 to maintain theshape of the first layer 21. For this purpose, the thickness of thesecond layer 22 is preferably set to at least 30 μm.

It is preferable for the resin material used for the first layer 21 tohave a good light transmissive property. It is also preferable to use athermosetting resin for the resin material. Preparing a slurry of asolvent, thermosetting resin, and solid particles of light reflectivesubstance, and curing the thermosetting resin by heating after spraycoating, can form a first layer 21 to a thickness in a stable mannereven at a high content of the solid particles of the light reflectivesubstance.

Such a resin material includes, for example, silicone resin, siliconemodified resin, epoxy resin, epoxy modified resin, urea resin, phenolicresin, polycarbonate resin, acrylic resin, polymethylpentene resin,polynorbornene resin, or a hybrid resin which contains one or more ofthese resins. Among all, a silicone resin or epoxy resin is preferable,and silicone resin which has good light resistance and heat resistanceis particularly more preferable.

For the second layer 22, any of the resin materials described for thefirst layer 21 can be used. The second layer 22, as in the case of thefirst layer 21, can be formed by not only spraying, but also molding,screen printing, or the like.

Although different resin materials can be used for the first layer 21and second layer 22, employing the same material for both can increasethe adherence between the first layer 21 and second layer 22.

Moreover, when forming the second layer 22, silica, or the like, may beadded to the slurry discussed above for the purpose of adjusting itsviscosity and fluidity.

Moreover, the resin used for the first layer 21 preferably has a higherrefractive index against the light emitted by the light emitting element1 than that of the resin used for the second layer 22.

This allows for the light that passes through the first layer 21 andpropagates towards the second layer 22 to be efficiently reflected atthe interface between the first layer 21 and second layer 22 based onSnell's law.

For the light reflective substances to be contained in the first layer21 and second layer 22, it is preferable to use particles of a materialhaving a refractive index significantly different from that of the resinmaterials described above, as well as having good transmissive property.

The refractive index of such a light reflective substance is at least1.8, for example In order to efficiently scatter the light and achieve ahigh extraction efficiency, the refractive index is preferably at least2.0, more preferably at least 2.5. The difference in the refractiveindices between the light reflective substance and a resin material is,for example, at least 0.4. In order to efficiently scatter the light andachieve a high extraction efficiency, the difference is preferably atleast 0.7, more preferably at least 0.9. The median particle size of thelight reflective substance particles is preferably at least 0.08 μm, but10 μm at most in order to achieve a scattering effect at highefficiency, more preferably at least 0.1 μm, but 5 μm at most.

For such a light reflective substance, TiO₂ (titanium oxide), ZrO₂(zirconium oxide), MgO (magnesium oxide), MgCO₃ (magnesium carbonate),Mg(OH)₂ (magnesium hydroxide), CaCO₃ (calcium carbonate), Ca(OH)₂(calcium hydroxide), CaSiO₃ (calcium silicate), ZnO (zinc oxide), BaTiO₃(barium titanate), Al₂O₃ (aluminum oxide), or the like, can be used.Among all, TiO₂ is preferable as it is relatively stable againstmoisture, has a high refractive index, and superior thermalconductivity.

In order to achieve even higher reflectance, it is preferable to useTiO₂ as the light reflective substance in cases where the light emittingelement 1 emits visible light, and Al₂O₃ for ultraviolet light.

Now, specific examples of the reflective indices of the first layer 21and second layer 22 of the light reflective member 2 will be explainedwith reference to FIG. 3. FIG. 3 shows the reflectance measured in theexperiment conducted where the reflective films for assumed uses in thefirst layer 21 and second layer 22 having various light reflectivesubstance contents and film thicknesses were prepared.

In this experiment, TiO₂ particles having a median particle size of 0.2μm were used as the light reflective substance, and a silicone resin wasused as the light-transmissive resin material to form the reflectivefilms. For the assumed use as the first layer 21, the reflective filmshaving a TiO₂ content of 95 mass % (plotted with white circles “o”) and60 mass % (plotted with black circles “”) were prepared by spraying.For the assumed usage as the second layer 22, the reflective filmshaving a TiO₂ content of 60 mass % (plotted with white squares “□”) and40 mass % (plotted with black squares “▪”) were prepared by transfermolding (TM).

As is clear from FIG. 3, the higher the content of the light reflectivesubstance, TiO₂, and the higher the film thickness, the higher thereflectance results.

Moreover, reflective films having TiO₂ contents of 95 mass %, 60 mass %,and 40 mass %, each having a thickness of 30 μm, were formed on the sidefaces of LED chips in Test Samples 1 to 3.

TABLE 1 shows the frontal emission outputs of the LEDs measured in theexperiment.

Now, the values for Test Samples 1 and 2 shown are relative valuesassuming that the LED emission output of Test Example 3 is “100.”

The reflective films in Test Samples 1 and 2 were formed by spraying,while that in Test Sample 3 was formed by transfer molding. The TestSamples 1-3 the results for which are shown in TABLE 1 were tested onlyby providing a reflective film in the thickness corresponding to thefirst layer 21.

TABLE 1 TiO₂ Film Test Forming Content Thickness Reflectance LED SamplesMethod (mass %) (μm) (%) Output (%) 1 Spraying 90 30 95 115 2 Spraying60 30 90 110 3 Transfer 40 30 80 100 Molding

As shown in TABLE 1, Test Sample 2 having a reflective film with a 60mass % content had a reflectance of 90%, and an light output of 110%, ascompared to the 80% reflectance of Test Sample 3 having a film with a40% content, which is conventionally used as a reflective film. TestSample 1 having a reflective film with a 95 mass % content, moreover,achieved a reflectance of 95% and an light output of 115%. It is clearfrom the experiment that a high reflectance can be achieved, and the LEDoutput in the frontal direction can be increased, by replacing a portionof the film thickness of a light reflective member having a conventionallight reflective substance content with a thin film having a highcontent of a light reflective substance.

Referring back to FIGS. 1 and 2, the explanation of the configuration ofthe light emitting device 100 will be continued.

The wavelength conversion member 3 is provided on the upper face of thelight emitting element 1, which is the light extraction face, and is alayer that contains a wavelength conversion substance that converts thelight emitted by the light emitting element 1 into light having adifferent wavelength.

Wavelength conversion substances are phosphors, and the wavelengthconversion member 3 can be formed by using, for example, alight-transmissive resin which contains phosphor particles. For theresin material, the same resin as that for the light reflective member 2discussed earlier can be used. Moreover, the wavelength conversionmember 3 can contain particles of a light diffusing substance in orderto impart light diffusion properties. For the light diffusing substance,any of the light reflective substances mentioned earlier can be used.

The thickness of the wavelength conversion member 3 can be determined inaccordance with the phosphor content, the color tone obtained aftermixing the light emitted from the light emitting element 1 with thelight after wavelength conversion, and the like. The thickness can beset, for example, to at least 1 μm, but 1000 μm at most, preferably atleast 5 μm, but 500 μm at most, and more preferably at least 10 μm, but200 μm at most.

In this embodiment, the wavelength conversion member 3 is provided toextend over the upper face of the light reflective member 2, but may beprovided only on the light emitting element 1. The wavelength conversionmember 3, moreover, is not an essential constituent element, and can beomitted. Alternatively, in lieu of the wavelength conversion member 3, alight diffusive member which contains a light diffusive substance, or atransparent layer which serves as a protective film, may be provided.

There are no particular limitations for the phosphors (wavelengthconversion substances) as long as the fluorescent substance is excitedby the light emitted by the light emitting element 1 and emits lighthaving a different wavelength than that of the excitation light, and aphosphor in particle form can suitably be used. Since phosphor particlesscatter and reflect light, they also function as a light scatteringmember in addition to converting the wavelength, achieving a lightdiffusion effect. Phosphors are preferably uniformly dispersed withinthe resin layer in which they are contained.

In cases where the wavelength conversion member 3 is formed by spraying,moreover, it is preferable to set the average particle size of thephosphor to about 2.5-30 μm so the prepared slurry of a solvent andthermosetting resin can be spray-coated. The average phosphor particlesize is determined in accordance with the air permeability method orFSSS (Fisher sub-sieve sizer) number (the so-called “D bar” (bar over D)value).

For the phosphor materials, any of those known in the art can be used.They include, for example, nitride-based phosphors, such ascerium-activated YAG (yttrium aluminum garnet)-based phosphors whichemits green to yellow light, cerium-activated LAG (lutetium aluminumgarnet) which emits green light, europium- and/or chromium-activatedcalcium aluminosilicate (CaO—Al₂O₃—SiO₂)-based phosphors which emitsgreen to red light, europium-activated silicate ((Sr,Ba)₂SiO₄)-basedphosphors which emits blue to red light, β-SiAlON phosphors which emitsgreen light, and CASN- or SCASN-based phosphors which emits red light;KSF (K₂SiF₆:Mn)-based phosphors which emits red light; and sulfide-basedphosphors which emits green or red light.

The phosphor materials, moreover, may be light emitting substancesreferred to as nanocrystals or quantum dots. Examples of these materialsinclude semiconductor materials, for example, II-VI, III-V, and IV-IVsemiconductors, more specifically nanosized highly dispersed particlesof CdSe, core-shell type CdS_(x)Se_(1-x)/ZnS, GaP, InAs, and the like.These phosphors can be set to a particle size, for example, of 1-100 nm,preferably about 1-20 nm (about 10-50 atoms). Using phosphors of theseparticle sizes can suppress the internal scattering, suppressing thescattering of the color-converted light thereby further increasing thetransmissive property of the wavelength conversion member 3.

The mounting substrate (substrate) 9 is a submount for mounting thelight emitting element 1 to convert it into a package. The mountingsubstrate 9 shown in FIG. 1 is an oblong rectangle in a plan view, andis configured with a tabular base 91, and wiring electrodes 92 n and 92p which are disposed at the left and right longitudinal ends of the base91 so as to bend around from the upper face to the lower face of thebase 91.

The mounting substrate 9 is formed in a size to include the lightemitting element 1 in a plan view. The wiring electrodes 92 n and 92 pare joined to the n-side electrode 13 and p-side electrode 15,respectively, via a conductive adhesive material 93 such as solder.

The light reflective member 2 which covers the side faces of the lightemitting element 1 is disposed on the upper face of the mountingsubstrate 9, so as to adhere its lower face thereto. The exposedsections of the wiring electrodes 92 n and 92 p are used as externalconnection terminals.

The mounting substrate 9 is not an essential element, and can beomitted. In cases where no mounting substrate 9 is provided, a CSP (chipsize package or chip scale package) type light emitting device can beconfigured by providing plated terminals on the n-side electrode 13 andp-side electrode 15 as external connection electrodes (see the fourthembodiment discussed later).

[Light Emitting Device Operation]

Subsequently, the operation of the light emitting device 100 will beexplained with reference to FIG. 1 (FIG. 2 when appropriate).

For the purpose of explanation, it is assumed that the light emittingelement 1 emits blue light, and the wavelength conversion member 3absorbs blue light and emits yellow light.

In the case of the light emitting device 100 shown in FIG. 1, the activelayer 12 a of the light emitting element 1 emits blue light when currentis supplied between the n-side electrode 13 and p-side electrode 15 froman external power supply via the wiring electrodes 92 n and 92 p of themounting substrate 9.

The blue light emitted by the active layer 12 a of the light emittingelement 1 propagates in the semiconductor stack 12 and growth substrate11 of the light emitting element 1 to be incident on the wavelengthconversion member 3 from the upper face of the light emitting element 1.The light laterally propagating in the light emitting element 1 isreflected by the light reflective member 2 into the light emittingelement 1, while the light propagating downwardly is reflected upwardlyby the full surface electrode 14, or the like, to be incident on thewavelength conversion member 3 from the light extraction face, which isthe substrate 11 side of the light emitting element 1. The lightpropagating towards the side faces of the light emitting element 1 isefficiently reflected primarily by the first layer 21 of the lightreflective member 2. The light that passes through the first layer 21 isreflected by the second layer 22.

One portion of the blue light incident on the wavelength conversionmember 3 is absorbed by the phosphors contained in the wavelengthconversion member 3, converted the wavelength into yellow light, andextracted from the light emitting device 100. At least a portion of therest of the blue light incident on the wavelength conversion member 3 isextracted from the light emitting device 100 as blue light as is,without being absorbed by the phosphors. From the light emitting device100, white light achieved by allowing yellow and blue light to be mixedis extracted.

[Producing Light Emitting Device Production]

The production method for the light emitting device 100 according to thefirst embodiment shown in FIG. 1 will be explained subsequently withreference to FIGS. 4-8.

As shown in FIG. 4, the production method for the light emitting device100 includes a semiconductor light emitting element preparation stepS101, mounting substrate preparation step S102, semiconductor lightemitting element mounting step S103, first layer forming step S104,second layer forming step S105, light reflective member removing stepS106, wavelength conversion member forming step S107, and singulationstep S108. The first layer forming step S104, second layer forming stepS105, and light reflective member removing step S106 make up the lightreflective member forming step.

First, in the semiconductor light emitting element preparation stepS101, the light emitting element 1 configured and singulated as shown inFIG. 2 is prepared. One example of the production method for the lightemitting element 1 will be explained below, but a commercially availablelight emitting element 1 may be obtained in place of the semiconductorlight emitting element preparation step S101.

More specifically, a semiconductor stack 12 is formed on a growthsubstrate 11 made of sapphire, or the like, by sequentially stacking ann-type semiconductor layer 12 n, active layer 12 a, and p-typesemiconductor layer 12 p using the semiconductor materials describedearlier.

After the semiconductor stack 12 is formed, a stepped section 12 b, inwhich the n-type semiconductor layer 12 n is exposed at the bottom, isformed in one region of the surface of the semiconductor stack 12 byetching off both the p-type semiconductor layer 12 p and active layer 12a entirely, and the n-type semiconductor layer 12 n partially.

Subsequently, a full surface electrode 14 having reflectance is formedin the light emitting region having the p-type semiconductor layer 12 pand active layer 12 a so as to cover substantially the entire upper faceof the p-type semiconductor layer 12 p.

Then, an insulator 16 made of SiO₂, or the like, is formed over theentire surface of the wafer by, for example, sputtering, so as to haveopenings 16 n and 16 p at the regions where an n-side electrode 13 willbe connected to the n-type semiconductor layer 12 n and where a p-sideelectrode 15 will be connected to the full surface electrode 14,respectively.

Subsequently, an n-side electrode 13, which is a pad electrode, isformed so as to extend from the opening 16 n to the upper face of theinsulator 16. A p-side electrode 15, which is a pad electrode, is alsoformed so as to extend from the opening 16 p to the upper face of theinsulator 16.

Wafer form light emitting elements 1 are formed by the steps describedabove.

Singulated light emitting elements 1 can be produced by splitting thewafer form light emitting elements 1 along predetermined regions bydicing, scribing, or the like.

The back face of the growth substrate 11 may be polished to reduce itsthickness prior to cutting the wafer. This can facilitate the cuttingstep.

Then, in the mounting substrate preparation step S102, the mountingsubstrates 9 shown in FIG. 5 are prepared. In the example shown in FIG.5, mounting substrates are prepared in the form of a substrate assembly90 where a plurality of mounting substrates 9 of the bases 91 arecontinuously formed. In this embodiment, moreover, a plurality of lightemitting devices 100 are simultaneously formed on the substrate assembly90 before they are singulated in the singulation step S108.

As shown in FIG. 5, the substrate assembly 90 is comprised of sixmounting substrates 9 arranged horizontally, and three arrangedvertically. In FIG. 5, individual regions of the mounting substrates 9are defined by dividing lines 81 and 82. Moreover, grooves 91 a arecreated along the dividing lines 82 on the substrate assembly 90 so asto pass through the bases 91 in the thickness direction. Thus, themounting substrates 9 have already been separated in the horizontaldirection. A pair of wiring electrodes 92 n and 92 p are provided incorrespondence with each mounting substrate 9 so as to extend from theupper face to the lower face of the base 91 via the groves 91 a. Therectangular regions of the wiring electrodes 92 n and 92 p located inthe central section of the upper face of each base 91 are connectingsections 92 na and 92 pa, respectively, to be connected to the n-sideelectrode 13 and p-side electrode 15 of the light emitting element 1.

The regions of the wiring electrodes 92 n and 92 p located at both endsof each base 91 in the longitudinal direction will serve as the regionsfor external connection during the secondary mounting.

As far as the semiconductor light emitting element preparation step S101and mounting substrate preparation step S102 are concerned, either stepmay precede the other, or they may be performed in parallel. Mountingsubstrates 9 may be prepared in a singulated format instead of asubstrate assembly 90 format. Moreover, the wiring electrodes 92 n and92 p of a mounting substrate 9 may be adapted so that the regions formedon the upper and lower faces of the base 91 are electrically connectedvia through holes provided in the thickness direction of the base 91.Alternatively, the wiring electrodes 92 n and 92 p of a mountingsubstrate 9 may be disposed only on the upper face of the base 91.

Then, in the semiconductor light emitting element mounting step S103,the light emitting element 1 is mounted on a mounting substrate 9 asshown in FIG. 6.

As illustrated in FIG. 6, the light emitting element 1 is flip chipmounted on the mounting substrate 9 by joining the n-side electrode 13with the connecting section 92 na of the wiring electrode 92 n, and thep-side electrode 15 with the connecting section 92 pa of the wiringelectrode 92 p, by using a conductive adhesive material 93, such assolder.

Subsequently, in the light reflective member forming step, a lightreflective member 2 is formed on the side faces of the light emittingelement 1. This step, as mentioned earlier, includes the first layerforming step S104, second layer forming step S105, and light reflectivemember removing step S106.

First, in the first layer forming step S104, the first layer 21 of thelight reflective member 2 is formed so as to cover the side faces of thelight emitting element 1 as shown in FIG. 7(a).

FIG. 7(a) is a sectional view at the position corresponding to line inFIG. 6(a). The same is true for FIGS. 7(b)-(d).

In this embodiment, as shown in FIG. 7(a), a coating is formed on thesurface of the light emitting element 1 by spraying a slurry spray 62comprised of a solvent which contains a thermosetting resin andparticles of a light reflective substance, by using a spraying device61. Heating the coating thereby curing the thermosetting resin can formthe first layer 21 in which the light reflective substance particles aretightly bound together.

Before spraying the slurry mentioned above, a masking tape 63 is appliedon the upper face of the mounting substrate 9, excluding the areas wherethe light emitting element 1 is mounted and its vicinity. The tape 63 isremoved after the coating step is completed. This can prevent thecoating from being formed in the regions of the upper face of themounting substrate 9 where the wiring electrodes 92 n and 92 p will beexternally connected. In this step, the coating is also formed on theupper face of the light emitting element 1 and in some portions of theupper face of the mounting substrate 9 in the vicinity of the lightemitting element 1 in addition to the side faces of the light emittingelement 1.

In this embodiment, moreover, the tape 63 is placed so as not to coverthe regions where the first layer 21 and second layer 22 will be formed.The tape 63 is not removed in this step, and is used as a frame forforming the second layer 22 in the following second layer forming stepS105. The tape 63 is not particularly limited to any kind as long as itis resistant to chemicals, such as the solvent used in the slurrydescribed above, and removable by being peeled off or dissolved by asuitable chemical.

As for the forming method for the first layer 21, besides the sprayingmentioned above, various other coating methods, such as inkjet, potting,screen printing, or the like, can be used. However, spraying ispreferable for high-precision coating of a resin material having a highcontent of light reflective particles. A pulsed spray method, which is acoating method to intermittently apply the spray 62, is particularlypreferable, as it can form the coating to a thickness with even higherprecision.

Now, the pulsed spray method will be explained.

Since the amount of material being sprayed can be reduced in pulsedspraying, a thin film can be formed with a reduced coating amount perspray application. By repeating spray applications multiple times, thecoating can be formed to a thickness with high precision. Moreover,using a thermosetting resin as the resin material, and pre-curing thethermosetting resin between multiple spray applications, such as everyapplication or predetermined number of applications (every three times,for example), can prevent the coating from becoming uneven due todripping or the like, producing a highly uniform coating with good filmthickness precision. Pre-curing herein means allowing a film to be curedto the extent that the thermosetting resin-containing slurry is nolonger fluid by heating at a temperature below the thermosetting resin'scuring temperature.

The slurry applied by the spraying device 61 contains a solvent,thermosetting resin, and particles of a light reflective phosphor. Theslurry is adjusted to an appropriate viscosity to the extent that it canbe sprayed.

For the thermosetting resin, any of the resin materials describedearlier can be used. For the solvent, an organic solvent, such asn-hexane, n-heptane, toluene, acetone, or the like, can be used.

The spraying device suitable for pulsed spraying and slurry coating areexplained in detail in Reference Materials 1 and 2, for example Thus,further explanation will be omitted.

(Reference 1) Japanese Unexamined Patent Application Publication No.S61-161175.

(Reference 2) Japanese Unexamined Patent Application Publication No.2003-300000.

Then, in the second layer forming step S105, a second layer 22 is formedso as to cover the outer side of the first layer 21, as shown in FIG.7(b). At this time, a resin layer having a lower content of theparticles of the light reflective substance than the first layer 21 isformed by using the tape 63 used in the previous first layer formingstep S104 as a frame. The second layer 22 is formed so that itsthickness becomes equivalent to the height of the upper face of thelight emitting element 1 or higher. The tape 63 is removed after formingthe second layer 22.

For the forming method for the second layer 22, any of the coatingmethods described to form the first layer 21 can be used. In cases whereemploying screen printing, or a forming method using a mold, or thelike, the tape 63 can be removed beforehand.

In cases where a thermosetting resin is used for both the first layer 21and second layer 22, it is preferable to pre-cure the first layer 21 inthe first layer forming step S104, and then fully cure the first layer21 together with the second layer 22 in the second layer forming stepS105. This can even more tightly join the first layer 21 and secondlayer 22 together.

Fully curing herein means allowing the thermosetting resin to becompletely cured by heating it at its curing temperature or higher.

Then, in the light reflective member removing step S106, the lightreflective member 2 (the first layer 21 and second layer 22) is removedto the height indicated by the cutting line 71 shown in FIG. 7(b), i.e.,the height of the upper face of the light emitting element 1, by using acutting device. This exposes the upper face, the light extraction face,of the light emitting element 1, patterning the light reflective member2 to cover only the side faces of the light emitting element 1, as shownin FIG. 7(c).

Subsequently, in the wavelength conversion member forming step S107, awavelength conversion member 3 is formed on the upper face of the lightemitting element 1 and the upper face of the light reflective member 2,as shown in FIG. 7(d). The wavelength conversion member 3 can be formedusing the same forming method as that for the first layer 21 and secondlayer 22 of the light reflective member 2. In the example shown in FIG.7(d), the wavelength conversion member 3 is formed by spraying a slurryspray 65 comprised of a solvent which contains thermosetting resin andphosphor particles (wavelength conversion substance), using a sprayingdevice 64.

In cases where a wavelength conversion member 3 is formed by spraying,it is preferable to preliminary cover the surface using, for example, amasking tape, excluding the upper faces of the light emitting element 1and light reflective member 2.

The wavelength conversion member 3 may be separately produced ahead oftime as a sheet material having a predetermined shape, and glued ontothe upper faces of the light emitting element 1 and light reflectivemember 2 by using a light-transmissive adhesive.

Then, in the singulation step S108, the light emitting devices 100 aresingulated by cutting the mounting substrates 9 and light reflectivemembers 2 along the dividing lines 81, as shown in FIG. 8(a). Asdiscussed earlier, the mounting substrates 9 have already been separatedby the grooves 91 a from adjacent light emitting devices 100 in thehorizontal direction. Thus, no cutting along the dividing lines 82 isnecessary.

Second Embodiment

[Light Emitting Device Configuration]

Subsequently, the light emitting device according to a second embodimentwill be explained with reference to FIG. 9.

As shown in FIG. 9, the light emitting device 100A according to thesecond embodiment is different from the light emitting device 100 in thefirst embodiment shown in FIG. 1 such that the wavelength conversionmember 3 is provided only on the upper face of the light emittingelement 1; a transparent layer 7 is provided on the upper face of thewavelength conversion member 3; and the light reflective member 2 isprovided to the height that covers the side faces of the wavelengthconversion member 3 and transparent layer 7.

In the light emitting device 100A, the wavelength conversion member 3 isprovided in the same region as that of the upper face of the lightemitting element 1 in a plan view, and its side faces are covered by thelight reflective member 2. Thus, the frontal emission luminance (upwarddirection in FIG. 9) can be further increased.

The transparent layer 7 is disposed to cover the entire upper face ofthe wavelength conversion member 3, and formed by a film using alight-transmissive resin material. For the resin material, the sameresin material as that used for the light reflective member 2 orwavelength conversion member 3 can be used.

The transparent layer 7 is provided for optically exposing thewavelength conversion member 3 without damaging the wavelengthconversion member 3 in the light reflective member removing step S206where the upper section of the light reflective member 2 is removed (seeFIG. 10).

The details of this step will be discussed later.

Light is extracted from the light emitting device 100A via thetransparent layer 7.

Except for that, the light emitting device 100A operates in the samemanner as the light emitting device 100, and thus the detailedexplanation of the same operation will be omitted.

[Producing Light Emitting Device]

Subsequently, the production steps for the light emitting element 100Aaccording to the second embodiment will be explained with reference toFIGS. 10 and 11.

As shown in FIG. 10, the production steps for the light emitting device100A includes a semiconductor light emitting element preparation stepS201, mounting substrate preparation step S202, semiconductor lightemitting element mounting step S203, first layer forming step S204,second layer forming step S205, light reflective member removing stepS206, and singulation step S207.

In this embodiment, the step for forming a wavelength conversion member3 is included in the semiconductor light emitting element preparationstep S201. The steps that are different from those for the firstembodiment will primarily be explained in detail below with reference toFIG. 11.

First, in the semiconductor light emitting element preparation stepS201, the light emitting elements 1 are prepared in the same manner asin the case of the semiconductor light emitting element preparation stepS101 in the first embodiment. In this step, before singulating the lightemitting elements 1, the wavelength conversion member 3 and transparentlayer 7 are formed by sequentially stacking them on the surface of thegrowth substrate 11 by spraying or the like. Then, by splitting thewavelength conversion member 3 and transparent layer 7 together with thelight emitting element 1, a singulated light emitting element 1A havingthe wavelength conversion member 3 and transparent layer 7 is prepared.

The mounting substrate preparation step S202 is the same as the mountingsubstrate preparation step S102 in the first embodiment, and thus theexplanation will be omitted.

Subsequently, in the semiconductor light emitting element mounting stepS203, the light emitting element 1A having the wavelength conversionmember 3 and transparent layer 7 is flip chip mounted on a mountingsubstrate 9 by joining the n-side electrode 13 with the connectingsection 92 na of the wiring electrode 92 n, and the p-side electrode 15with the connecting section 92 pa of the wiring electrode 92 p, by usingan adhesive material 93 as shown in FIG. 11(a).

Subsequently, the first layer forming step S204 and second layer formingstep S205 are performed in the same manner as in the first layer formingstep S104 and second layer forming step S105 in the first embodiment,respectively. By these steps, the light reflective member 2 is formed soas to cover the side and upper faces of the light emitting element 1A.

Then, in the light reflective member removing step S206, the lightreflective member 2 is cut and removed to the height indicated by thecutting line 73 in FIG. 11(b). This optically exposes the upper face ofthe wavelength conversion member 3, which is the light extraction face,from the light reflective member 2 as shown in FIG. 11(c). Opticallyexposing herein means that the transparent layer 7 may be present on theupper face of the wavelength conversion member 3.

The height of the cutting line 73 is set between the lower and upperends of the transparent layer 7. Although it depends on the method, highfilm thickness precision can be more readily achieved for the wavelengthconversion member 3 by spraying than by cutting. Accordingly, damagingthe wavelength conversion member 3, which has been formed on the upperface of the light emitting element 1 with high precision, in thesubsequent cutting step would partially or entirely change the colortone.

In this embodiment, therefore, the light extraction face is opticallyexposed from the light reflective member 2 by forming a transparentlayer 7, and then cutting and removing the light reflective member 2within the range of the thickness of the transparent layer 7.

The thickness of the transparent layer 7 can be set depending on thecutting precision so it is thicker than that corresponds to the cuttingprecision.

The singulation step S207 can be performed in the same manner as in thecase of the singulation step S108 in the first embodiment, and thus theexplanation will be omitted.

The light emitting device 100A shown in FIG. 9 is produced as describedabove.

Third Embodiment

[Light Emitting Device Configuration]

Subsequently, the light emitting device according to a third embodimentwill be explained with reference to FIG. 12.

As illustrated in FIG. 12, the light emitting device 100B according tothe third embodiment is different from the light emitting device 100 inthe first embodiment shown in FIG. 1 such that it has a light reflectivemember 2B instead of the light reflective member 2. In the lightreflective member 2B, the first layer 21B is provided on the side facesof the light emitting element 1 via a resin rich layer 23.

The first layer 21B, as in the case of the first layer 21 in the firstembodiment, has a high content of light reflective substance. When ithas a high content of particles of the light reflective substance (forexample, 95 mass % or higher), it might not sufficiently adhere to thelight emitting element 1 on occasion. In this embodiment, therefore, aresin rich layer 23 which has a low light reflective substance content,that is, high resin content, is provided between the first layer 21B andthe light emitting element 1 to increase the adhesion between the two.

For the resin rich layer 23, the same resin material as that for thelight reflective member 2 can be used. The resin rich layer does notneed to contain any light reflective substance, but when it does, thecontent is preferably lower than that of the first layer 21B, as well asbeing the same as, or lower than, that of the second layer 22. Moreover,in order to increase the light reflection efficiency of the first layer21B, it is preferable to make the resin rich layer 23 thin to the extentthat it achieves good adhesion between the first layer 21B and the lightemitting element 1. For this purpose, the thickness of the resin richlayer 23 is preferably about the same as, or thinner than, the firstlayer 21B. More specifically, the thickness of the resin rich layer 23is preferably at least 1 μm, but 10 μm at most.

The resin rich layer 23 can be formed using various coating methods asin the case of the first layers 21 and 21B described earlier. Pulsedspraying is particularly preferable for uniformly forming the resin richlayer 23 even thinner.

The light emitting device 100B operates the same way as the lightemitting device 100 in the first embodiment, and thus the explanationwill be omitted.

[Producing Light Emitting Device]

The light emitting device 100B can be produced by following theproduction method for the light emitting device 100 in the firstembodiment, except for forming a resin rich layer 23 after thesemiconductor light emitting element mounting step S103, but before thefirst layer forming step S104.

More specifically, the resin rich layer 23 is formed by spraying, or thelike, so as to cover the surface of the light emitting element 1 beforeforming a first layer 21B in the first layer forming step S104.

In cases where a thermosetting resin is used as the resin materials forthe resin rich layer 23 and first layer 21B, it is preferable to allowthe resin rich layer 23 applied on the surface of the light emittingelement 1 to be air-dried or pre-cured, and then allow it to be fullycured after applying the first layer 21B. This can tightly adhere thelight emitting element 1 to the first layer 21B via the resin rich layer23. The other steps are the same as those in the first embodiment, andthus the explanations will be omitted.

The light emitting device 100B shown in FIG. 12 is formed as describedabove.

The configuration where the first layer 21B is provided on the sidefaces of the light emitting element 1 via the resin rich layer 23 isalso applicable to the light emitting device 100A according to thesecond embodiment.

Forth Embodiment

[Light Emitting Device Configuration]

Subsequently, the configuration of the light emitting device accordingto a fourth embodiment will be explained with reference to FIG. 13.

As shown in FIG. 13, the light emitting device 100C according to thefourth embodiment have a light emitting element 1C, light reflectivemember 2C, wavelength conversion member 3, light-transmissive member 4,supporting member 5, and external connection electrodes 6 n and 6 p.

The light emitting device 100C differs from the light emitting device100 shown in FIG. 1 such that it has a light-transmissive member 4disposed on the side faces of the light emitting element 1C, and thelight reflective member 2C is disposed to cover the side faces of thelight emitting element 1C via the light-transmissive member 4.

The light emitting device 100C also differs from the light emittingdevice 100 in the following respects.

The light emitting device 100C has external connection electrodes 6 nand 6 p, and supporting member 5, instead of a mounting substrate 9,which is a submount, to configure a CSP type package. The light emittingelement 1C used in the light emitting device 100C, moreover, is roughlya square in a plan view.

The same reference numerals are assigned to the same constituentelements as those for the light emitting device 100 for which theexplanations will be omitted whenever appropriate.

Although the light emitting element 1C has a different outer shape fromthe light emitting element 1 shown in FIG. 1, it is a flip chip mountingtype LED chip having the same cross sectional structure as shown in FIG.2. The plan view shape of the light emitting element 1C is notparticularly limited, and may be a rectangle as in the case of the lightemitting element 1.

The light-transmissive member 4 is provided on the side faces of thesemiconductor stack 12 and growth substrate 11, which are the side facesof light emitting element 1C (see FIG. 2).

At the bottom of the light emitting element 1C, the external connectionelectrode 6 n which is electrically connected to the n-side electrode13, the external connection electrode 6 p which is electricallyconnected to p-side electrode 15, and supporting member 5, which isdisposed to enclose the perimeters of the external connection electrodes6 n and 6 p in a plan view, are provided.

The light-transmissive member 4 is provided in contact with the sidefaces of the light emitting element 1C so as to surround the outerboundary of the light emitting element 1C in a plan view, and is afillet for reflective the light exiting from the side faces of the lightemitting element 1C in the upward direction, which is the lightextracting direction. For this purpose, the light-transmissive member 4has an outer face sloping outwardly in the light extracting directionwith respect to the thickness direction of the light emitting element 1Cin a plan view. By providing such a light-transmissive member 4, thelight exiting from the side faces of the light emitting element 1 can beextracted more efficiently.

In the example shown in FIG. 13(b), the outer face of thelight-transmissive member 4 is planar so it's cross sectional shape is astraight line. The outer face, however, is not limited to this, and maybe curved to be downwardly or upwardly concave.

The outer face of the light-transmissive member 4, moreover, is coveredby the first layer 21C of the light reflective member 2C, and on theupper face of the light-transmissive member 4, the wavelength conversionmember 3 is provided continuously from the section on the upper face ofthe light emitting element 1. The light exiting from the upper face ofthe light-transmissive member 4 is extracted via the wavelengthconversion member 3.

The light-transmissive member 4 can be formed using a material havinggood transmissive property, such as a resin, glass, or the like.Moreover, it is preferable to form the light-transmissive member 4 usinga material having a higher refractive index than the resin material usedfor the first layer 21C of the light reflective member 2C. Constructingthe light-transmissive member 4 with a material of higher refractiveindex than the first layer 21C can efficiently reflect the light at itsouter face which interfaces with the first layer 21C based on Snell'slaw.

The light-transmissive member 4 can be formed by supplying a liquid orpaste resin material on the side faces of the light emitting element 1C,for example, using a dispenser, and subsequently allowing it to becured.

The light reflective member 2C has a two-layer structure consisting of afirst layer 21C and second layer 22C, and is disposed so as to cover theside faces of the light-transmissive member 4 to reflect the lightexiting from the outer face of the light-transmissive member 4 againstthe light-transmissive member 4. In other words, the light reflectivemember 2C is provided so as to cover the side faces of the lightemitting element 1 via the light-transmissive member 4. Accordingly, thefirst layer 21C is provided so as to cover the outer face of thelight-transmissive member 4, and the second layer 22C is provided so asto cover the outer face of the first layer 21C.

In the example shown in FIG. 13(b), moreover, the light reflectivemember 2C is disposed so that its bottom face has the same height asthat of the bottom face of the supporting member 5.

The first layer 21C and second layer 22C can be formed by using the samematerials and methods as those for the first layer 21 and second layer22 in the first embodiment, respectively.

The wavelength conversion member 3 is disposed so as to cover the upperfaces of the light emitting element 1, light-transmissive member 4, andlight reflective member 2. Since the only difference between thewavelength conversion member 3 in this embodiment and that in the firstembodiment is its outer shape, and thus the detailed explanation will beomitted.

The supporting member 5 is disposed at the bottom face of the lightemitting element 1C, the electrode forming face, so as to surround theexternal connection electrodes 6 n and 6 p in a plan view to support theexternal connection electrodes 6 n and 6 p. The supporting member 5 canbe formed by using an insulating resin. The employment of a lightsensitive material used as a photoresist is preferable as it enables thepatterning of the supporting member 5 by photolithography. Moreover, itis preferable to use a heat resistant material for the supporting member5 that is formed around the external connection electrodes 6 n and 6 pso as not to be deformed or denatured during mounting while using anadhesive material such as solder. A resin material, such assilicone-based resin, epoxy-based resin, or polyimide-based resin, forexample, can be suitable used.

The external connection electrodes 6 n and 6 p are electrode terminalsto connect the light emitting element 1C to an external power supply.The upper face of the external connection electrode 6 n is electricallyconnected to the n-side electrode 13, while the lower face is used forexternal connection. Similarly, the upper face of the externalconnection electrode 6 p is electrically connected to the p-sideelectrode 15, and the lower face is used for external connection.

The external connection electrodes 6 n and 6 p can be formed, forexample, as plated posts by way of electroplating. The externalconnection electrodes 6 n and 6 p can also be formed by using metalwires. For the external connection electrodes 6 n and 6 p, it ispreferable to use a metal material having good electrical and thermalconductivity, such as Cu, Au, or the like.

[Light Emitting Device Operation]

Subsequently, the operation of the light emitting device 100C will beexplained with reference to FIG. 13 (see FIG. 2 when appropriate).

For the purpose of explanation, it is assumed that the light emittingelement 1C emits blue light, and the wavelength conversion member 3absorbs the blue light and emits yellow light.

In the case of the light emitting device 100C shown in FIG. 13, theactive layer 12 a of the light emitting element 1C emits blue light whencurrent is supplied between the n-side electrode 13 and p-side electrode15 from an external power supply via the external connection electrodes6 n and 6 p.

The blue light emitted by the active layer 12 a of the light emittingelement 1C propagates in the semiconductor stack 12 and growth substrate11, and is extracted from the upper face of the light emitting element1C via the wavelength conversion member 3. The light propagatinglaterally in the light emitting element 1C becomes incident on thelight-transmissive member 4, is reflected upwardly at the outer surfacewhere the light reflective member 2C is disposed, and extracted via thewavelength conversion member 3. The light propagating downwardly in thelight emitting element 1C is reflected upwardly by the full surfaceelectrode 14 or the like, and extracted via the wavelength conversionmember 3.

One portion of the blue light incident on the wavelength conversionmember 3 is converted into yellow light by the wavelength conversionmember 3 to be extracted from the light emitting device 100C, while atleast another portion of the blue light is extracted as blue light asis, without being converted. Thus, from the light emitting device 100C,white light achieved by allowing yellow and blue light to be mixed isextracted.

[Producing Light Emitting Device]

Subsequently, the production method for the light emitting device 100Caccording to the fourth embodiment shown in FIG. 13 will be explainedwith reference to FIG. 14.

As shown in FIG. 14, the production method for the light emitting device100C includes a semiconductor light emitting element preparation stepS301, semiconductor light emitting element mounting step S302,light-transmissive member forming step S303, first layer forming stepS304, second layer forming step S305, light reflective member removingstep S306, sheet removing step S307, wavelength conversion memberforming step S308, and singulation step S309. The first layer formingstep S304, second layer forming step S305, and light reflective memberremoving step S306 make up the light reflective member forming step.

First, in the semiconductor light emitting element preparation stepS301, a supporting member 5 and external connection electrodes 6 n and 6p are formed to prepare a singulated light emitting element 1C.

For this purpose, light emitting elements 1C are prepared first byfollowing the same procedures as in the semiconductor light emittingelement preparation step S101 in the first embodiment (see FIG. 4).

Then, on the electrode forming face of the light emitting element 1C, asupporting member 5 is formed by photolithography using a photoresist.At this point, the supporting member 5 is patterned so as to haveopenings in the regions where the external connection electrodes 6 n and6 p will be formed.

Then, a metal layer which will be an electroplating seed layer is formedon the supporting member 5, including the openings mentioned above, forexample, by sputtering.

Subsequently, a metal plated layer to form the external connectionelectrodes 6 n and 6 p is formed inside the openings in the supportingmember 5 by electroplating using the seed layer as the electrical path.

Then, the upper faces of the supporting member 5 and the metal platedlayer are cut at a predetermined height to form a light emitting element1C equipped with the supporting member 5 and external connectionelectrodes 6 n and 6 p.

Alternatively, the steps up to the formation of the supporting member 5and external connection electrodes 6 n and 6 p may be performed by awafer-level step, followed by the singulation of the light emittingelements 1C.

Then, in the semiconductor light emitting element mounting step S302,the light emitting elements 1C equipped with the supporting member 5 andexternal connection electrodes 6 n and 6 p are mounted on a sheet 66having an adhesive surface so that the growth substrate 11 andsemiconductor stack 12 face down as shown in FIG. 15. In the exampleshown in FIG. 15(a), three pieces of light emitting elements 1C arearranged both vertically and horizontally at predetermined intervals.The number of light emitting element 1C mounted may be one, or a largernumber than those shown.

In FIG. 15(a), the regions defining individual light emitting devices100C are shown by dividing lines 81 and 82.

Subsequently, in the light-transmissive member forming step S303, alight-transmissive member 4 is formed on the side faces of lightemitting element 1C, that is, the side faces of the growth substrate 11and semiconductor stack 12, so as to enclose the outer periphery of thelight emitting elements 1C in a plan view, as shown in FIG. 16.

The light-transmissive member 4 can be formed, for example, by supplyinga light-transmissive resin material using a dispenser, or the like, incontact with the side faces of the light emitting element 1C, andsubsequently curing the resin material. It is preferable to form thelight-transmissive member 4 with an outer face sloping down outwardlytowards the light extraction surface (the bottom face of the lightemitting element 1C in FIG. 16(b)) in a plan view. Such a shape can beformed by supplying a resin material having an appropriate viscosity atthe corner of the side face of the growth substrate 11 of the lightemitting element 1C and upper face of the sheet 66, and allowing thegravity to spread towards the bottom to be cured. Alternatively, theouter face shape may be molded using a mold, followed by curing.

Then, in the light reflective member forming step, a light reflectivemember 2C is formed so as to cover the outer face of thelight-transmissive member 4. This step includes, as mentioned earlier,the first layer forming step S304, second layer forming step S305, andlight reflective member removing step S306.

First, in the first layer forming step S304, a first layer 21C of thelight reflective member 2C is formed so as to cover the outer face ofthe light-transmissive member 4, as shown in FIG. 17(a). The first layer21C is formed by using a spraying device 61 as in the case of the firstembodiment.

In this step, the first layer 21C is formed by coating across the entiresurfaces of the light-transmissive member 4, supporting member 5, andexternal connection electrodes 6 n and 6 p which have been disposed onthe sheet 66.

FIG. 17(a) shows a cross section at the location corresponding to lineV-V in FIG. 15(a). The same is true for FIGS. 17(b)-(d) and FIG.18(a)-(b).

Subsequently, in the second layer forming step S305, a second layer 22Cis formed so as to cover the outer side of the first layer 21C as shownin FIG. 17(b). At this point, a resin layer having a lower lightreflective particle content than the first layer 21C is formed.Moreover, the second layer 22C is formed in the thickness so its heightis the same as, or higher than, the upper faces of the externalconnection electrodes 6 n and 6 p.

For the second layer 22C, the same forming method as in the case of thefirst embodiment can be used, and thus the explanation will be omitted.

Then, in the light reflective member removing step S306, the lightreflective member 2C (first layer 21C and second layer 22C) is removedto the height shown by the cutting line 72 in FIG. 17(b), that is, theheight of the upper faces of the external connection electrodes 6 n and6 p, by using a cutting device. This exposes the upper faces of theexternal connection electrodes 6 n and 6 p, which will be the sectionsused for external connection, patterning the light reflective member 2Cto cover the side faces of light emitting element 1C via thelight-transmissive member 4, as shown in FIG. 17(c).

Then, in the sheet removing step S307, the sheet 66 which is a supportfor the light emitting element 1C is removed as shown in FIG. 17(d).Since multiple light emitting elements 1C are connected by the lightreflective member 2C at this point, they can maintain the arrayed stateeven when the sheet 66 is removed.

Subsequently, in the wavelength conversion member forming step S308, awavelength conversion member 3 is formed on the light extraction faceside of the light emitting element 1C and light-transmissive member 4,as shown in FIG. 18(a). In FIG. 18(a), the light emitting element 1C isoriented upside down relative to FIG. 17(d). Accordingly, the lightextraction face of the light emitting element 1C is shown as the top inFIG. 18(a).

The wavelength conversion member 3 can be formed in the same manner asin the case of the first embodiment, and thus the detailed explanationwill be omitted.

Then, in the singulation step S309, as shown in FIG. 18(b), the lightemitting devices 100C are singulated by cutting the wavelengthconversion member 3 and light reflective member 2C along the dividinglines 82 and 81 (see FIG. 15(a)).

The light emitting element 100C shown in FIG. 13 is prepared asdescribed above.

Fifth Embodiment

[Light Emitting Device Configuration]

Subsequently, the configuration of the light emitting device accordingto a fifth embodiment will be explained with reference to FIG. 19.

As shown in FIG. 19, the light emitting device 100D according to thefifth embodiment is different from the light emitting device 100C in thefourth embodiment shown in FIG. 13 such that it has a light-transmissivemember 4D instead of the light-transmissive member 4.

In the light emitting device 100D, the light-transmissive member 4D isdisposed to integrally cover the upper face of the light emittingelement 1C in addition to the side faces. Accordingly, the wavelengthconversion member 3 is disposed on the upper face of the light emittingelement 1C via the light-transmissive member 4D.

The other constituent elements are the same as those of the lightemitting device 100C in the fourth embodiment, and thus the explanationswill be omitted.

In the light emitting device 100D, among the light emitted by the lightemitting element 1C, the light upwardly propagating in the lightemitting element 1C becomes incident on the wavelength conversion member3 via the light-transmissive member 4D. Except for that, it operates thesame way as in the case of the light emitting device 100C in the fourthembodiment, and thus the detailed explanation of the operation will beomitted.

[Producing Light Emitting Device]

Subsequently, the production method for the light emitting device 100Daccording to the fifth embodiment shown in FIG. 19 will be explainedwith reference to FIGS. 20 and 21.

As shown in FIG. 20, the production method for the light emitting device100D includes a semiconductor light emitting element preparation stepS401, light-transmissive member coating step S402, semiconductor lightemitting element mounting step S403, first layer forming step S404,second layer forming step S405, light reflective member removing stepS406, sheet removing step S407, wavelength conversion member formingstep S408, and singulation step S409. The first layer forming step S404,second layer forming step S405, and light reflective member removingstep S406 make up the light reflective member forming step.

The semiconductor light emitting element preparation step S401 isperformed in the same manner as in the case of the semiconductor lightemitting element preparation step S301 in the fourth embodiment.

Then, in the light-transmissive member coating step S402, a liquid resinmaterial is applied as the light-transmissive member 4D by a coatingmethod, such as potting, inkjet, or the like, on the sheet 66 in theregion where a light emitting element 1C will be mounted (see FIG. 21(b)), as shown in FIG. 21(a). Here, the coating of the liquidlight-transmissive member 4D formed on the sheet 66 bulges over the topby surface tension.

Subsequently, in the semiconductor light emitting element mounting stepS403, a light emitting element 1C is mounted on the liquidlight-transmissive member 4D as shown in FIG. 21(b). At this point, thelight emitting element 1C sinks into the liquid light-transmissivemember 4D by its own weight, and as a result, its bottom and side facesare covered by the light-transmissive member 4D. Now, in thelight-transmissive member coating step S402, the coated area, amount,viscosity, and the like, of the liquid light-transmissive member 4D areadjusted so that the bottom and side faces of the light emitting element1C will be covered by the light-transmissive member 4D. It is preferableto use a thermosetting resin for the light-transmissive member 4D inorder to easily make such adjustments.

Moreover, the light-transmissive member 4D is cured in the conditionwhere the bottom and side faces of the light emitting element 1C arecovered by the light-transmissive member 4D. In cases where athermosetting resin is used for the light-transmissive member 4D, it canbe cured by air-drying and/or heating.

The subsequent first layer forming step S404, second layer forming stepS405, light reflective member removing step S406, and sheet removingstep S407 are performed in the same manner as in the case of the firstlayer forming step S304, second layer forming step S305, lightreflective member removing step S306, and sheet removing step S307 inthe fourth embodiment, respectively.

Then, in the wavelength conversion member forming step S408, awavelength conversion member 3 is formed on the upper face of thelight-transmissive member 4D, which is the light extraction face, asshown in FIG. 21(c). The wavelength conversion member 3 can be formed inthe same manner as in the case of the wavelength conversion memberforming step S308 in the fourth embodiment, and thus the detailedexplanation will be omitted.

In FIG. 21(c), the light emitting element 1C after the sheet removingstep S407 is oriented so the light-transmissive member 4D is shown atthe top.

In the singulation step S409, the light emitting devices 100D aresingulated by cutting the wavelength conversion member 3 and lightreflective member 2C along the dividing lines 82 and the like, as in thecase of the singulation step S309 in the fourth embodiment.

The light emitting device 100D shown in FIG. 19 is formed as describedabove.

<Variants>

In the light emitting device 100 shown in FIG. 1, the light reflectivemember 2 has a two-layer structure where the first layer 21 and secondlayer 22 are stacked, but it may constructed by stacking multiple setsof the first layer 21 and second layer 22 so they alternate. This canmake a light reflective member 2 having even higher reflectance. Even inthese cases, it is preferable to form the first layer 21 with a resinmaterial having a higher refractive index than that of the resinmaterial used in the second layer. This enables the utilization ofinterfacial reflection based on Snell's law, and can further increasethe reflectance of the light reflective material 2.

Similarly in the light emitting devices 100A, 100B, 100C, and 100D inthe other embodiments, the light reflective member 2, or the like, maybe constructed by stacking multiple sets of the first layer 21, or thelike, and the second layer 22, or the like, so they alternate.

The light emitting devices and the production method of the inventionhave been specifically explained based on several embodiments forrealizing the invention in the foregoing. The present invention,however, is not limited to these disclosures, and must be broadlyinterpreted based on what is set forth in the scope of the claimssection. It goes without saying that various modifications andvariations made based on these disclosures are within the spirit andscope of the invention.

What is claimed is:
 1. A method of manufacturing a light emittingdevice, the method comprising: providing a structure comprising: asubstrate that includes a first wiring electrode and a second wiringelectrode located at an upper surface of the substrate, a light emittingelement mounted on the upper surface of the substrate, a wavelengthconversion member disposed on or above an upper surface of the lightemitting element, a light-transmissive member disposed on an uppersurface of the wavelength conversion member, and a light reflectivemember disposed on each side surface of the light emitting element, thewavelength conversion member and the light-transmissive member anddisposed on an upper surface of the light-transmissive member, removinga portion of the light reflective member and a portion of thelight-transmissive member that are located in a region that extends froman upper surface of the light reflective member to a position betweenthe upper surface and a lower surface of the light-transmissive member.2. The method of manufacturing a light emitting device according toclaim 1, wherein, after removing said portion of the light reflectivemember and said portion of the light-transmissive member, a thickness ofthe light-transmissive member is less than a thickness of the wavelengthconversion member.
 3. The method of manufacturing a light emittingdevice according to claim 1, wherein said portion of the lightreflective member and said portion of the light-transmissive member areremoved such that, after the removing step, an upper surface of thelight reflective member is coplanar with the upper surface of thelight-transmissive member.
 4. The method of manufacturing a lightemitting device according to claim 1, wherein the light reflectivemember includes silicone resin and TiO₂.
 5. The method of manufacturinga light emitting device according to claim 1, wherein the wavelengthconversion member includes a phosphor adapted to emit red light and aphosphor adapted to emit green light.
 6. The method of manufacturing alight emitting device according to claim 5, wherein the phosphor adaptedto emit red light is a KSF-based phosphor, and the phosphor adapted toemit green light is a β-SiAlON-based phosphor.
 7. The method ofmanufacturing a light emitting device according to claim 1, wherein thelight emitting device further comprises an additional light-transmissivemember located between the light emitting element and the wavelengthconversion member.
 8. The method of manufacturing a light emittingdevice according to claim 7, wherein the additional light-transmissivemember covers the upper surface of the light emitting element and aportion of a side surface of the light emitting element.